Z3 2.5l Overheating

Ajsbored94

Ajsbored94

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Sep 23, 2020
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Drove it down to the beach and back today (almost 9 hours of constant driving on the interstate at 3.5k rpms) and noticed on my return trip it started to overheat. It would go up, then down, then up. It would raise as the rpms went up, and cool down when idle or less than 2k rpms. It only just touched the 2/3rd marker and hardly went past it.

Is this normal for the m52? Water pump? Possible broken/worn hoses? I'll be looking at it more in the morning but just wanting some second opinions on what I should check out.
 
:welcome: to the forum from West Cumbria, England. Replacing with the Water Pump and associated parts seems most logical, replace it with a non plastic one, longer life.
 
andyglym said:
:welcome: to the forum from West Cumbria, England. Replacing with the Water Pump and associated parts seems most logical, replace it with a non plastic one, longer life.
Click to expand...
How long would it take to replace the water pump? Is it invasive?
 
Ajsbored94 said:
How long would it take to replace the water pump? Is it invasive?
Click to expand...
Not sure how long but it's not a quick job and if it's still the original pump you may/may not have issues extracting due to possible seized fixings. If you're good with the spanners it's a doable DIY, if not, take it to a garage. Not a lot of room either so I think some may remove the radiator. Whilst you're in there you may as well do the thermostat, serpentine belt, pulleys and tensioners.

@t-tony @Lee @Stevo7682

Spanners ain't my thing, these guys are however Guru's so will be able to advise better.

This may help?

zroadster.org

BMW Z3 M52TU Thermostat Replacement by Mike Fishwick

BMW Z3 M52TU Thermostat Replacement Article reproduced with kind permission of Mike Fishwick When the M52TU double-VANOS versions of the established M52 engine were introduced in September 1998, it featured a cooling system thermostat which was...
zroadster.org zroadster.org
 
To change the water pump on an E85 Z4 you have to do 1of 2 things. Remove the front end of the car (bumper, radiator etc.) or jack the engine up of it mountings.
There are several videos on YouTube showing how it’s done.
Personally I would replace the thermostat before doing anything else, a job which can be done relatively easily. I did a “How to” earlier this year. I changed mine because the rubber “O” ring seal had failed.

Tony.
 
t-tony said:
To change the water pump on an E85 Z4 you have to do 1of 2 things. Remove the front end of the car (bumper, radiator etc.) or jack the engine up of it mountings.
There are several videos on YouTube showing how it’s done.
Personally I would replace the thermostat before doing anything else, a job which can be done relatively easily. I did a “How to” earlier this year. I changed mine because the rubber “O” ring seal had failed.

Tony.
Click to expand...
This is a 2.5 Z3 Tony
 
Didn’t spot that Andy, saw 2.5 only. Advice much the same even so. Thermostat first!

Tony.
 
Thanks guys, I got up under the car and see that I'm leaking coolant from the main crank pulley. I know its not coming from there, but I do think its the waterpump that's just above it that's causing me to lose coolant. Is there any other explanation to what could be leaking aside from the water pump? Photo attached is the crank pulley and water coming off of it.
 

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Water pumps are bad if they are leaking water or they produce bearing noise/squealing in extreme cases.
Most overheating issues are due to low coolant levels, the thermostat sticking, and clogged radiators.
 
t-tony said:
To change the water pump on an E85 Z4 you have to do 1of 2 things. Remove the front end of the car (bumper, radiator etc.) or jack the engine up of it mountings.
There are several videos on YouTube showing how it’s done.
Personally I would replace the thermostat before doing anything else, a job which can be done relatively easily. I did a “How to” earlier this year. I changed mine because the rubber “O” ring seal had failed.

Tony.
Click to expand...

Just to avoid any confusion going forward you don’t need to do either of these things with the water pump replacement. On the Z3 and z4 the pump can be accessed above via the front once you remove the Vicous fan. The only difference is the Z4SI models where the pump is Electic and on the bottom.
 
Lee said:
Just to avoid any confusion going forward you don’t need to do either of these things with the water pump replacement. On the Z3 and z4 the pump can be accessed above via the front once you remove the Vicous fan. The only difference is the Z4SI models where the pump is Electic and on the bottom.
Click to expand...

The E85 Z4 doesn’t have a viscous fan? It does however have a large steel bracket which doesn’t leave enough room to withdraw the water pump from the block. The thermostat is located above the water pump so, if like mine, the seal (gasket) has failed it will still drip off the crank pulley.

Tony.
 
My mistake not spotting that this was a US 2.5 Z3. However just so there is no confusion, changing the water pump on an E85 Z4 is not a straight forward job. I will add some pictures to this later.
20201002_171818.webp

Here's the water pump on my Z4, you can se from the rusty thread that they don't have a viscous fan. There is 1.25 inches between the end of the thread and the steel cross brace.
20201002_172018.webp

Here's the new water pump for my car, there is almost 3 inches of pump inside the block.

Tony.
 
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That’s strange Tony. I’ve done 2 on Z4’s and yeah it’s very tight but manage to extract it downwards into a gap in the brace. Double nut the lower studs to get them out the way.
 
mwpe said:
On the Z3 6 cylinder the water pump is quite easy. Just remove the viscous fan, fan shroud and the serpentine belt. and the pump is easily accessible.

BMW Z3 Water Pump Replacement | 1996-2002 | Pelican Parts DIY Maintenance Article

Leaking or faulty water pump? This tech article shows you how to replace the water pump on 4 and 6-cylinder Z3 models.
www.pelicanparts.com
Click to expand...

Tony thought he meant Z4. It’s very easy on Z3’s but more difficult on Z4’s because of the front shroud.
 
Hey guys, some more info. The leak is coming from the water pump. I had the car running and saw the water pump pulley moving back and forth. It has play when the car is off also, as if the pulley is not fastened down. I believe the water pump pulley/mechanical fan pulley play has caused the water pump to fail and begin leaking so i will be replacing it as soon as the new pump/pulley/fan comes in the mail. Im hoping the timing cover is not also leaking but my oil looks fine, not milky.
 
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